Leviticus 6:16-17

16And Aaron and his sons are to eat 1what is left of it. It shall be eaten as unleavened cakes in a holy place; they are to eat it in the courtyard of the tent of meeting.

172It shall not be baked with leaven. I have given it as their share from My offerings by fire; 3it is most holy, like the sin offering and 4the guilt offering.